IMMUNOLOGY - Ocular Clinical Immunology Flashcards
What is the main immunoglobulin in human tears?
IgA
What are the DNA viruses (7)
- Adenovirus
- Herpes SIMPLEX virus
- Varicella ZOSTER virus
- Epistein Barr virus
- Cytomegalovirus
- Molluscum contagiosum virus
- Vaccinia and variola virus
Aill Happy Viruses Enter Cells, Making Vaccines Valuable
What are RNA viruses? (5)
RNA Pathogens frequently threaten the public
1. Picorna virus (Polio, Coxsackie, Hepatitis A, Rhinovirus)
- Flavi virus (Dengue, Yellow, Zika, Japanese encephalitis, Hep C)
- Filo virus (Ebola)
- Toga virus (Rubella)
- Paramyxo virus (Measles, Mumps, RSV, parainfluenza - mighty respiratory pathogens)
Which virus is the most common cause of conjunctivitis? Which subtype?
Adenovirus (DNA) –> mostly belong to subgroup D (A-F classification) –> usually type 8, 19 and 37 –> type 8 is classic cause of EKC
What is the systemic effect of leukotrienes? (3)
- Bronchoconstriction
- Vasoconstriction
- Increase vascular permeability
–> involved in allergic reactions and inflammation
What is the main complement implicated in AMD?
Factor H. This checks complement cascade at C3 and C5 induction.
Which cells are associated with sympathetic ophthalmia?
TH1 lymphocytes (CD4)
Which cells are associated with parasite induced granulomas?
TH2 lymphocytes (CD4)
What type of immune cell is associated with birdshot choroidoretinopathy?
TH17 (CD4)
What do tears contain to fight off bacteria and which type of bacteria are more effective against?
Lysozymes - more effective against gram-negative bacteria
What happens in steven johnson’s syndrome? What type? What immunodeficiencies occur?
Type 4 hypersensiivity reaction caused by cytotoxic reaction against keratinocytes that express foreign antigens.
- Granulysin secretion by cytotoxic T cells
- Drug-specific CD8+ expansion and infiltration into dermoepidermal junction
- TNF protein activation induces cell apoptosis
- Epithelial damage causing sloughing of mucous membranes
5.
What is MALT? Where is it present and what predominant antibody does it produce? What happens after antigen presentation?
Mucosal Associated Lymphoid Tissues –> collection of subepithelial lymphocytes, APCs (dendritic cells) and lymphoid tissue not contained within a capsule.
Present on mucosal surfaces (such as conjunctiva and ocular adnexal glands).
Predominant immunoglobulin produced is IgA. Rarely, lymphoma arises from this tissue.
Antigen exposure stimulates IgA at all mucosal surfaces. B-cells and T-cells express homing receptors for addressins which direct movement of cells to various mucosal sites
What is the therapeutic use of Interferon Alpha, Interferon beta, Interferon gamma
Alpha: Viruses (HBV, HCV, HHV-8 (Kaposi Sarcoma) , HTLV-2 (B cell leukaemia)
Beta: Multiple sclerosis
Gamma: chronic granulomatous disease
Corneal graft rejection is what type of hypersensitivity reaction?
Type 4.
Which antigen is associated with cancer-associated retinopathy syndrome?
Recoverin - calcium-binding protein which inhibits rhodopsin phosphoylation
What antigen is involved in leber congenital amaneurosis and retinitis pigmentosa?
RPE65 - plays role in vitamin A metabolism
Which antigen is found in VKH syndrome?
Tyrosinase - found in melanocytes.
Where are APCs found in ocular tissues? What quality do normal APCs have that ocular APCs don’t have?
Limbus, ciliary & iris epithelium, ciliary muscle, processes and TM
Dendritic cells found at ora serrata in neural retina and in connective tissue aroudn choriocapillaries
Ocular APCs cannot activate T cells like conventional APCs
What components are contained in the aqueous?
What is its main function (2)
BACTERIOSTATIC PROPERTIES
1. Complement
2. Immunoglobulin
3. Defensins
4. Beta-Lysin
Immunosuppress: inhibit T-cell proliferation (via TGF-beta), inhibits lymphokine production and suppresses macrophage and APC activityto allow for ocular immune privilege
What is ocular immune privilege? What are its components? (4)
Protects ocular structures from potentially damaging immune-mediated inflammation
- Blood-ocular barrier
- Lack of lymphatics to the eye
- Soluble immune modulatory mediators in aqueous
- Unique tolerance promoting APCs
What is the process of corneal angiogenesis? What does it respond to?
Response to inflammation promoted by fibrin and its degradation products.
- Latent - vasodilation, vascular permeability of neighbouring vessels, stromal oedema
- Endothelial activation (24 hours), the endothelium retracts and nucleoli enlarge
- Endothelial basement membrane/basal lamina broken down by plasminogen activator which is produced by fibroblasts, macrophages and others
- Vascular sprouting - sprouts from post-capillary venules and capillaries
- Vascular maturation - deposition of ECM and laminin and basal lamina/basement membrane formation
Which immunomodulators are contributory to ocular immune privilege?
TGF-B, IL-10 (immunosuppressive)
NK T cells mediate their activity
